60 



AGRICULTURAL CHEMISTRY. 



Now, according to the analysis of Bous- | smell. 100 

 singault, which merits the greatest confi- horse bein 

 dence, hay contains one per cent, of nitro- 

 gen ; consequently in the 25 Ibs. of hay 

 which a cow consumes daily, of a Ib. of 

 nitrogen must have been assimilated. This 



quantity of nitrogen entering into the com- 

 position of muscular fibre would yield 8*3 

 Ibs. of flesh in its natural condition.* The 

 daily increase in size of a cow is, however, 

 much less than this quantity. We find that 

 the nitrogen., apparently deficient, is actually 

 contained in the milk and urine of the ani- 

 mal. The urine of a milch-cow contains 

 less nitrogen than that of one which does 

 not yield milk ; and as long as a cow yields 

 a plentiful supply of milk, it cannot be fat- 

 tened. We must search for the nitrogen of 

 the food assimilated, not in the solid, but in 

 the liquid excrements. The influence which 

 the former exercise on the growth of vege- 

 tables does not depend upon the quantity of 

 nitrogen which they contain. For if this 

 were the case, hay should possess the same 

 influence ; that is, from 20 to 25 Ibs. ought 

 to have the same power as 100 Ibs. of fresh 

 cow-dung. But this is quite opposed to all 

 experience. 



Which then are the substances in the ex- 

 crements of the cow and horse which exert 

 an influence on vegetation ? 



When horse-dung is treated with water, 

 a portion of it to the amount of 3 or 3^ per 

 cent, is dissolved, and the water is coloured 

 yellow. The solution is found to contain 

 phosphate of magnesia, and salts of soda, 

 besides small quantities of organic matters.f 

 The portion of the dung undissolved by the 

 water yields to alcohol a resinous substance 

 possessing all the characters of gall which 

 has undergone some change; while the 

 residue possesses the properties of saw-dust, 

 from which all soluble matter has been ex- 

 tracted by water, and burns without any 



* 100 Ibs. of flesh contain on an average 15'86 

 of muscular fibre : 18 parts of nitrogen are con- 

 tained in 100 parts of the latter. 



t Dr. C. T. Jackson in his "Geological and 

 Agricultural Survey of Rhode Island," (page 205.) 

 gives the following analysis of horse-dung : 50C 

 grains, dried at a heat a little above that of boiling 

 water, lost 357 grains of water. The dry mass 

 weighing 143 grains was burned, and left 8*5 grains 

 of ashes, of which 4'80 grains were soluble in 



dilute nitric acid, and 3 '20 insoluble, 

 being analysed, gave 



Silica .... 



Phosphate of lime 



Carbonate of lime 



Phosphate of magnesia and soda 



The ashes 



3-2 

 0-4 

 1-5 



2-9 



8-0 



It consists, then, of the following ingredients : 

 Water .... 357'0 



Vegetable fibre and animal matter 135-0 

 Silica . ... 3'2 



Phosphate of lime . . 0'4 



Carbonate of lime . . . T5 



Phosphate oi magnesia and soda . 29 



500-0 



parts of the fresh dung of a 

 dried at 100 C. (212 F.) 

 eave from 25 to 30 or 31 parts of solid sub- 

 stances, and contained, accordingly, from 69 

 :o 75 parts of water. From the dried ex- 

 crements, we obtain, by incineration, vari- 



able quantities of salts and earthy matters, 

 according to the nature of the food which 

 las been taken by the animal. Macaire and 

 Vlarcet found 27 per cent, in the dung ana- 

 ysed by them; I obtained only 10 per cent, 

 rom that of a horse fed with chopped straw, 

 oats, and hay. It results then that with 

 >om 3600 to 4000 Ibs. of fresh horse-dung, 

 corresponding to 100 Ibs. of dry dung, we 

 place on the land from 2484 to 3000 Ibs. of 

 water, and from 730 to 900 Ibs. of vegetable 

 matter and altered gall, and also from 100 

 to 270 Ibs. of salt and other inorganic sub- 

 stances. 



The latter, are evidently the substances to 

 which our attention should be directed, for 

 they are the same which formed the compo- 

 nent parts of the hay, straw, and oats with 

 which the horse was fed. Their principal 

 constituents are the phosphates of lime and 

 magnesia, carbonate of lime and silicate of 

 potash; the first three of these preponde- 

 rated in the corn, the latter in hay. 



Thus in 1000 Ibs. of horse-dung, we pre- 

 sent to a field the inorganic substances con- 

 tained in 6000 Ibs. of hay, or 8300 Ibs. oi 

 oats (oats containing 3'1 per cent, ashes ac- 

 cording to De Saussure.) This is sufficient 

 to supply l crop of wheat with potash and 

 phosphates. 



The excrements of cows,* black cattle, 

 and sheep, contain phosphate of lime, com- 

 mon salt, and silicate of lime, the weight of 

 which varies from 9 to 28 per cent., accord- 

 ing to the fodder which the animal receives ; 

 the fresh excrements of the cow contain 

 from 86 to 90 per cent, of water. 



Human faeces have been subjected to an 

 exact analysis by Berzelius. When fresh 

 they contain, beside f of their weight oi 

 water, nitrogen in very variable quantity, 

 namely, in the minimum 1|, in the maxi- 



* It has been formerly stated (page 41) that all 

 the potash contained in the food of a cow is again 

 discharged in its excrements. The same also 

 takes place with the other inorganic constituents 

 of food, either when they are not adapted for as- 

 similation, or when present in superabundant 

 quantities. The value of manure may thus be 

 artificially increased. We lately saw, for ex- 

 ample, some cow-dung, sent by a farmer, who 

 wished to ascertain the cause of its increased 

 value. He had formerly employed this manure 

 for his land, but with so little advantage that he 

 found it more profitable to dry it, and use it as 

 fuel. On inquiry, it was found, that his cows had 

 been fed upon oil-cake. This species of food 

 is particularly rich in phosphates. More of these 

 salts being present than were requisite for the 

 purpose of assimilation, they were removed from 

 the system in the form of excrementitious matter, 

 and in a condition adapted for the uses of plants. 

 The fact that particular kinds of food enrich or 

 impoverish the manure obtained from the cattle fed 

 upon them, has repeatedly been observed. Ei> 



